The purpose of this proposal is to investigate the effects of orthographic structure on feature integration in word perception. An adequate account of word perception must describe how visual features are integrated into appropriate units of analysis and identify these units. In the proposed studies human observers will be briefly presented strings of colored letters. Veridical perception of the stimulus displays depends on the correct integration of color and letter-shape information. Errors in correctly combining color and shape information will be used to study perceptual units in word perception. It has been found that visual features within a perceptual unit are more likely to be incorrectly combined than features in different perceptual units where the units are described by the Gestalt principles (see Appendix). If short words are processed as units, but unrelated letter strings are processed letter by letter, then one would expect more incorrect combinations of letter shape and color in wrods than in nonwords. In a preliminary study we have confirmed this prediction with words and unpronounceable nonwords. The first goal of this research is to address several alternative explanations of this pilot research and to explore the problem of measuring errors of feature integration. The second goal of this research is to examine meaningfulness and pronounceability as the factors that might account for the greater number of feature integration errors in words than in nonwords. The final goal of this research is to test alternative proposals for units within words. Proposals for reading units have been made based on phonology (spelling units, syllables) and morphology (morphemes). If these units play a role in visual perception, then there should be more incorrect combinations of color and letter shape within a unit (spelling unit, syllable, morpheme, etc.) than errors between units. This research will help understand word perception and also how cognitive factors influence the integration of color and shape information.